Centrifugal countercurrent exchange device with fully adjustable apertures



Nov. 16, 1965 w. G. PODBIELNIAK ETAL 3,

CENTRIFUGAL COUNTERCURRENT EXCHANGE DEVICE WITH FULLY ADJUSTABLE APERTURES 3 Sheets-Sheet 1 Filed April 12 1963 INVENTORS K W m E g BY mm /W GM E L0 w W M N 1965 w. G. PODBIELNIAK ETAL 17,

CENTRIFUGAL COUNTERCURRENT EXCHANGE DEVICE WITH FULLY ADJUSTABLE APERTURES Filed April 12, 1963 3 Sheets-Sheet 2 t MN 0L mmm E v VDO m A mm u mom w fl 1965 w. G. PODBIELNIAK ETAL 3,217,930

CENTRIFUGAL COUNTERCURRENT EXCHANGE DEVICE WITH FULLY ADJUSTABLE APERTURES 3 Sheets-Sheet 3 Filed April 12, 1963 INVENTORS WLADZJA G. PODBIELNIAK BXFOLUN M DOYLE.

FLH 5.

United States Patent 3,217,980 CENTRIFUGAL COUNTERCURRENT EX- CHANGE DEVICE WITH FULLY ADJUST- ABLE APERTURES Wladzia G. Podbielniak and Collin M. Doyle, both of 632 N. Dearborn St., Chicago, IlL; said Wladzia G. Podbielniak now by marriage Wladzia G. P. Doyle Filed Apr. 12, 1963, Ser. No. 272,718 20 Claims. (Cl. 233-45) This invention relates generally to centrifugal countercurrent exchange devices of the type disclosed in the copending application of Wladzia G. Podbielniak entitled Centrifugal Countercurrent Exchange Device With Interchangeable Disc Columns, filed November 1, 1961, Serial No. 149,425, now Patent 3,114,706, issued December 17, 1963. More particularly, it pertains to a centrifugal countercurrent exchange device having means rendering the same universally adaptable and efiiicacious for all known fluid systems and industries in which such devices may be employed.

As described in the aforementioned co-pending application, the single most important function of centrifugal countercurrent exchange devices is their ability to cause the fluids or liquids flowing therethrough to thoroughly mix, or effect completely intimate contact, one with the other. As a matter of fact, it is now irrefutably clear, based upon experimentation and the very nature of the liquid-liquid extraction process, that the efficiency of any extract-ion device is totally dependent upon and directly proportional to the degree of intimate mixing of the liquids which is achieved. Accordingly, it is likewise clear that the provision of means for varying or controlling the ability of such a device to intimately mix any and all liquids which may be processed therethrough is of paramount importance.

It is of course apparent to those skilled in the art that the successful practice of any liquid extraction process necessarily entails the consideration of, and provision for, numerous characteristics inherent in the process. Included among such inherent characteristics are the following:

(l) The volumetric ratio of the liquids to each other. (2) The difference in viscosity of the liquids.

(3) The miscibility or immiscibility of the liquids. (4) The difference in surface tension of the liquids. (5) The difference in specific gravity of the liquids. (6) The tendency of the liquids to emulsify.

Another important consideration in determining the commercial feasibility of an extraction device is the volumetric throughput capacity of the device.

Briefly stated, centrifugal countercurrent exchange devices of the type under consideration comprise simply a rotor having a plurality of apertured concentric bands permanently positioned therein. The liquids being processed in such a device must of course flow through the apertures in each of the concentric bands. Those skilled in the art will thus recognize that for a given machine, control over, and/or compensation for, changes in the above listed inherent characteristics and considerations could be achieved if means were devised for adjusting, as required, the pattern, size and/ or total area of the apertures in the bands.

3,217,980 Patented Nov. 16, 1965 Prior to the aforementioned co-pending application, the exchange devices available afiforded little or no control over the most important and desirable factor of aperture adjustability. Thus, all of the prior devices had a fixed, or substantially fixed, aperture pattern, size and area. As a result, each of these expensive devices necessarily was tailor-made for a single extraction process in which the inherent characteristics and considerations were of course not subject to variation. So long as the contemplated specific process was practiced therein, the prior device could achieve a relatively high degree of efiiciency, However, when it was attempted to practice a different process in such a tailor-made machine-one, for example, in which the new liquids had different characteristics of viscosity, specific gravity or emulsificationthat machines efficiency was sharply reduced, sometimes to the point of complete inoperativeness.

A vivid example of the above-described situation recently occurred in connection with a centrifugal countercurrent exchange device used by a pharmaceutical manufacturer in a process for the extraction of penicillin from fermented liquor by the use of various solvents. The de vice was originally designed for a process in which the solvent com-prised amyl acetate. Subsequently, further developments and discoveries in the process indicated that chloroform as a solvent was more desirable because of its greater selectivity and the fact that it could be used at higher ratios. However, when it was attempted to sub stitute, :as a solvent, chloroform for the original amyl acetate, the machine became inoperable. Further investigation disclosed that the chloroform readily formed an emulsion when mixed with the fermented liquor, and that the chloroform was more viscous and higher in specific gravity than amyl acetate. Thus, it became readily apparent that the new chloroform system required a radical change in droplet dispersion and mixing energy. In fact, it required a machine with considerably larger orfiices or apertures in the bands. Since at that time the only machines available were those in which the aperture openings were fixed, it was necessary for the manufacturer to purchase another machine with larger fixed orifices. The new machine, of course, worked entirely satisfactorily. However, had the original machine been capable of changing the size of the orifices or apertures therein, it would have been a simple matter to adapt the original machine for use in the new chloroform-fermented liquor system.

Heretofore, in the processing of certain liquids, especially those containing living organisms, the problem of emulsification sometimes arose between different batches of the same system. In such case, demulsificants or wetting agents were sometimes used in attempts to control the emulsion. This involved extensive research, expensive auxiliary equipment, considerable time, and did not produce uniform good results. With the present invention, variation of the droplet dispersion (apertures) and mixing energy (r.p.m.) invariably solves the problem without emulsificants.

The devices disclosed in the aforementioned co-pending application contributed greatly to solving the problem of aperture adjustability. In those devices, the concentric bands were formed with a plurality of aligned relatively large holes to afford a plurality of radial cavities. Into the cavities were removably insertable interchangeable disc columns which themselves comprised a plurality of spaced apart discs whose aperture characteristics could be changed or adjusted as desired. The interchangeable and adjustable disc columns thereby imparted a considerable degree of flexibility to the exchange device so that the same could be readily adapted, within limits, to operate efiiciently with a variety of different processes and liquid systems. However, a great need still existed for an exchange device having simpler means for substantially unlimited control and adjustability of the aperture characteristics and ensuing mixing energy.

It is therefore an important object of this invention to provide a centrifugal countercurrent exchange device which overcomes all of the shortcomings and disadvantageous features described hereinabove.

Another object of the invention is to provide a centrifugal countercurrent exchange device having means for substantially unlimited adjustability of the aperture characteristics and thus, substantially unlimited control over the mixing energy within the device.

In accordance with the invention, all customary tiny apertures or perforations are eliminated from the concentric bands. Instead, the bands are provided solely with elongated apertures extending longitudinally over a substantial portion of the Width of the bands. Means are then provided for covering said elongated apertures with removable aperture strips. The aperture strips are interchangeable and may be formed with any desired aperture pattern, size or area, or they may even be imperforate to completely seal off the elongated apertures. Control over the aperture and mixing energy adjustability is thus complete and limited only by the size and maximum throughput capacity of the device.

Another object of the invention is to provide a centrifugal countercurrent exchange device of the character described in which the adjustment of the aperture characteristics may be readily and simply accomplished by simple, inexpensive interchangeable means. A related object is to provide such a device which is universally adaptable for virtually all extraction processes and liquid systems and yet requires very little down time to change over from one system to another.

Still another object is to afford a centrifugal countercurrent exchange device of the character described having means for adjustably effecting rotary or linear droplet dispersion of the liquids in addition to the radial droplet dispersion thereof. Thorough and intimate mixing of the liquids may thus be even further enhanced.

A further object is to provide a centrifugal countercurrent exchange device which is more costly to fabricate than prior similar devices, and yet is most efficient and durable for the purposes intended.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel features of construction, arrangements and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the form, proportion, size and minor details of the structure may be made without departing from the spirit or sacrificing any of the advantages of the invention.

1 For the purpose of facilitating an understanding of our invention, We have illustrated in the accompanying drawings preferred embodiments thereof, from an inspection of which, when considered in connection with the following description, our invention, its mode of construction, assembly and operation, and many of its advantages should be readily understood and appreciated.

Referring to the drawings in which the same characters of reference are employed to indicate corresponding or similar parts throughout the several figures of the drawmgs:

FIG. 1 is a fragmentary vertical sectional view of a centrifugal countercurrent exchange device embodying the principles of the invention;

FIG. 2 is a sectional view taken on the plane of line 22 in FIG. 1 and viewed in the direction indicated, with portions broken away to illustrate the relationship of parts;

FIG. 3 is an enlarged fragmentary sectional view taken on the plane of line 33 in FIG. 2, viewed in the direction indicated and illustrating a detail of construction;

FIG. 4 is an enlarged fragmentary sectional view taken on the plane of line 44 in FIG. 1, viewed in the direction indicated;

FIG. 5 is an enlarged detailed view of the segment indicated by the circle in FIG. 4;

FIG. 6 is a fragmentary perspective view of a segment of one of the bands showing the elongated aperture formed therein, and with portions being broken away to show the aperture-strip retaining means positioned therebelow;

FIGS. 7 through 10 are perspective views of aperturestrips with a variety of possible aperture characteristics, with FIG. 10 additionally illustrating an aperture-strip having means for effecting rotary or linear droplet dispersion;

FIG. 11 is a fragmentary and elevational view of the rotor and illustrating a modified form of access port; and

FIG. 12 is a fragmentary sectional view taken on the plane of line 1212 in FIG. 11 and viewed in the direction indicated.

Turning now to FIG. 1 of the drawings, the reference numeral 10 indicates generally a centrifugal countercurrent exchange device embodying the principles of the invention. Since the basic device It is generally of the type described in the aforementioned co-pending application, or well known in the prior art, and does not per se comprise the specific subject of the invention, only so much thereof as is necessary for an understanding of the subject invention will be described. The device 10 thus comprises a shaft 12 suitably journalled for rotation in a supporting structure such as 14. A drum or rotor 16 is rigidly connected to the shaft 12 for rotation therewith, and the entire device may be enclosed by a removable protective cover such as 18.

Suitable passageways such as 20 and 22 are provided in the shaft 12 for respectively supplying the heavier liquid to the central area of the drum 16 and removing the lighter liquid therefrom. Similarly, suitable passageways such as 24 and 26 are provided for respectively supplying the lighter liquid under pressure to the peripheral area of the drum 16 and removing the heavier liquid therefrom. A connecting passageway (not shown) may be provided through which the heavier liquid may flow from the periphery of the drum to the discharge passageway 26.

The drum 16 comprises a cylindrical outer wall 30, and as indicated in FIGS. 1 and 2, the same may be solid over its entire area and completely imperforate. Similarly, the drum 16 includes a pair of end plates 32 and 34, one of which (32) is preferably solid over the entire area thereof and free of all openings. It is important to note, however, that the opposite end plate 34 is provided with a plurality of ports or access holes 36 for purposes which will become apparent as the description proceeds. The ports 36 may be internally threaded and adapted to receive threaded locking or sealing plugs such as 38, said plugs being provided with tool-accommodating recesses such as 40. In the embodiment illustrated (see FIG. 2), the access holes 36 are arranged over the entire surface of the end wall 34 in radially projecting rows spaced approximately 22 /2" apart, although other arrangements or spacings thereof may likewise be employed. It is important only that the holes 36 afford symmetrical or balanced access to all of the concentric separator bands within the rotor for reasons which will likewise become apparent as the description proceeds.

Permanently mounted within the rotor 16 is a plurality of concentric separator bands 42, and as described in the aforementioned co-pending application, the spacing between the bands 42 preferably should increase with increasing radius, or at least be uniform. The separator bands 42 may be mounted in the usual manner, such as by positioning the ends thereof within properly spaced and sized concentric grooves cut in the end walls 32 and 34. Within each of the access holes 36 may be removably positioned a disc 44 comprising a section of the end wall 34 and which is likewise formed with grooves adapted to accommodate the ends of the bands 42 therein (see FIG. 3). A sealing gasket 46 may likewise be positioned in each of the access holes 36. It is important, however, to recognize here that when a plug 38 and its associated disc 44 is removed from an access hole 36, there are exposed the free ends of a number of the separator bands 42. The number of band ends thus exposed is of course dependent upon the size of the hole 36 and the spacing between the bands.

Referring now more particularly to FIGS. 4 through 6 of the drawings, it will be noted that the bands 42 are completely devoid of all perforations or other similar small openings. Instead, the bands are formed with a plurality of aligned transverse rows of openings or elongated apertures 48. The rows of elongated apertures 48 may extend in spaced relationship substantially the full width of the bands 42, but leaving webs between each slot and between each row of slots. Similarly, the apertures are preferably straight in projection and may be approximately wide by 1" long with approximately a web between each slot.

Secured to the inner (under) surface of the bands 42 adjacent each aperture 48 is a pair of opposed channel members 50, 50. The channel members 50 may be substantially coextensive with the apertures 48, and the same are adapted to snugly but removably support therebetween a novel aperture strip such as 52, 52a, 52b or 520, shown respectively in FIGS. 7 through 10 of the drawings. The aperture strips are of sufficient length to completely cover the elongated apertures 48, and the same may be provided with any desired size or arrangement of apertures such as 54, 54a and 54b. The trailing end of each of the aperture strips may likewise be provided with a tool hole such as 56, 56a, 56b and 56c respectively for cooperating with a suitable tool such as a hook when it is desired to remove the strip from its associated channel.

Referring particularly to the strip 52c (FIG. 10) it will be seen that the strips may likewise be made imperforate or Without any apertures therein. It is important to note, however, that the strip 52c is instead provided with an elongated and upstanding rib 58 secured medially thereto. The rib 58 may be provided with any size or pattern of apertures such as 60, and it will be appreciated that the same is adapted to either project up through its associated elongated aperture 48 and into the space between the adjacent pair of bands 42 or depend therefrom in inverted position. The rib 60 thus effects rotary or linear droplet dispersion of the liquids between the bands if so desired.

It will of course be appreciated that the aperture-strips 52 are interchangeable and that the size, pattern and total area of apertures which may be formed in the individual strips is virtually unlimited. Similarly, the strips may be made imperforate and/or with upstanding ribs such as 58 for effecting droplet disperson of the liquids in the spaces between the separator bands. The novel aperture strips thus cooperate with the elongated apertures 48 in the bands to readily provide all possible aperture characteristics needed or desired. In the latter regard, it will be appreciated that in order to change the aperture characteristics of the device, it is simply necessary to remove some or all of the plugs 38 and discs 40. The affected strips are removed as by means of a suitable hook, and new strips with the desired aperture characteristics operationally inserted into the channel members 50. It should further be appreciated that by positioning the strips 52 below the bands 42, a tight fitting relationship between the strips and the bands are maintained by reason 6. of the centrifugal force exerted thereon during operation of the machine.

In FIGS. 11 and 12 there is shown a slightly modified form of the rotor end wall 34 in which similar; parts are designated by similar reference numerals with the suffix a added thereto. Thus, the end wall 34a is formed with a lesser number of considerably larger pie-shaped access holes or ports such as 36a in lieu. of the previous circular access holes 35. Removably positionable in each of the openings is a pie-shaped plug such as 38a which may be operationally retained by any suitable means such as the screws 62. The disc 44a and gasket 46a are of course likewise suitably shaped to suit the pie-shaped openings 36a. In the embodiment illustrated there are only 6 equally spaced pie-shaped "openings 36a, and it will be appreciated that the removal of one of the considerably larger plugs 33a (and disc 44a) results in the exposure of a considerably larger number of bands 42 and aperture strips 52. This of course greatly facilitates the interchange of the aperture strips.

From the foregoing description and drawings, it should be apparent Without further description that we have provided a centrifugal countercurrent exchange device having novel but simple and inexpensive means rendering the device universally adaptable for virtually any extraction process or fluid system. This universality is of course the result of the cooperation between the elongated apertures 48 and the readily interchangeable strips 52 which enable a single machine to achieve a multitude of differing aperture characteristics. Rotary or linear droplet dispersion may likewise be achieved in addition to radial dispersion. Moreover, the adjustment of aperture characteristics may be quickly and simply made with a minimum of down time.

It is believed that our invention, its mode of construction and assembly, and many of its advantages should be readily understood from the foregoing; without further description, and it should also be manifest that while preferred embodiments of the invention have been shown and described for illustrative purposes, the structural details are nevertheless capable of wide variation within the purview of our invention as defined in the appended claims.

What we claim and desire to secure by Letters Patent of the United States is:

1. In a centrifugal countercurrent exchange device, including a rotor having a pair of end Walls and a plurality of concentric separator bands positioned in said rotor, means for supplying heavier liquid to and means for removing lighter liquid from the interior of said rotor in the proximity of the axis thereof, and means for forcing lighter liquid into and means for discharging heavier liquid from the interior of said rotor in the proximity of the periphery thereof; the herein improvement comprising means removably associated with said separator bands for adjusting the aperture characteristics thereof, and removable means in one of said end walls affording access to said bands for making said adjustments.

2. The centrifugal countercurrent exchange device of claim 1 in which said bands are formed with a plurality 'of elongated apertures, and said first mentioned means comprises an elongated strip adapted to cover said elongated apertures.

3. The centrifugal countercurrent exchange device of claim 2 in which retaining means are secured to said bands adjacent each of said elongated apertures, said retaining means adapted to operationally retain said strip in aperture-covering relationship, and said strips having a plurality of apertures formed therein.

4. The centrifugal countercurrent exchange device 'of claim 3 in which said one end wall is provided with a plurality of access ports, and said second mentioned means comprises a plug removably positioned, one in each of said access ports.

5. The centrifugal countercurrent exchange device of claim 4 in which a disc is removably positioned in each of said access ports, said disc comprising a cut-out section of said end wall and being provided with a plurality of grooves adapted to accommodate therein the free edges of said bands.

6. A centrifugal countercurrent exchange device comprising a rotor having an outer cylindrical wall and a pair of end walls, a plurality of concentric bands permanently mounted in said rotor, said bands being imperforate save for a plurality of elongated transverse apertures formed therein, interchangeable means removably associated with said bands for obtaining any desired droplet dispersion within said rotor, retaining means on said bands for operationally retaining said first mentioned means, and access means in one of said end walls for affording access to said bands.

7. The centrifugal countercurrent exchange device of claim 6 in which said first mentioned means comprises a plurality of thin strips adapted to cover said elongated apertures, at least some of said strips being formed with varying sizes, patterns and total areas of apertures therethrough.

8. The centrifugal countercurrent exchange device of claim 7 in which some of said strips are imperforate.

9. The centrifugal countercurrent exchange device of claim 7 in which an elongated rib is secured medially to some of said strips, said ribs being formed with varying aperture characteristics and adapted to project into the spaces between said bands for effecting linear droplet dispersion of liquids in said rotor.

10. The centrifugal countercurrent exchange device of claim 7 in which said second-mentioned means comprises a pair of opposed elongated channel members secured to the inner surfaces of said bands adjacent each of said elongated apertures, said channel members slidably engaging the lateral edges of said strips for retaining the same in operational position.

11. The centrifugal countercurrent exchange device of claim 10 in which said last-mentioned means comprises a plurality of access ports formed in said one end wall and arranged so that access is provided to all of said bands and elongated apertures, and a sealing plug removably positioned in each of said access ports.

12. The centrifugal countercurrent exchange device of claim 11 in which said access ports are annular in configuration, a circular disc removably positioned in each of said ports and comprising a cut-out section of said one end wall, said disc being provided with a plurality of spaced grooves adapted to engage the free edges of said bands.

13. The centrifugal countercurrent exchange device of claim 11 in which said access ports are radian shaped, a radian shaped disc removably positioned in each of said ports and comprising a cut-out section of said one end wall, said disc being provided with a plurality of spaced grooves adapted to engage the free edges of said bands.

14. A centrifugal countercurrent exchange device comprising a rotor having an imperforate outer cylindrical wall and a pair of end walls, a plurality of concentric separator bands permanently mounted in said rotor with the marginal edges thereof being received in concentric grooves formed in said end walls, said bands being formed with a plurality of rows of elongated apertures spaced one from the other and extending substantially but less than the distance between said end walls, said bands being otherwise imperforate, a pair of opposed elongated channel members secured to the inner surface of said bands adjacent each of said rows of elongated apertures, a plurality of elongated strips having varying aperture characteristics formed therethrough, each of said strips being slidably engageable in one of said pairs of opposed channel members to cover the adjacent row of elongated apertures and thereby afford complete adjustability over the being arranged so that access is provided to all of said bands and elongated apertures, a disc removably positioned in each of said ports and comprising a cut-out section of said one end wall, and a sealing plug removably positioned in each of said ports and bearing against said disc when operationally positioned.

15. In a centrifugal countercurrent exchange device, including a rotor having a pair of end walls and spaced partition walls positioned in said rotor, means for supplying heavier liquid to and means for removing lighter liquid from the interior of said rotor in the proximity of the axis thereof, and means for forcing lighter liquid into and means for discharging heavier liquid from the interior of said rotor in the proximity of the periphery thereof; the herein improvement comprising means removably associated with said partition walls for adjusting the aperture characteristics thereof, and removable means in one of said end walls affording access to said partition walls for making said adjustments.

16. A centrifugal countercurrent exchange device comprising a rotor having an outer cylindrical wall and a pair of end walls, spaced separator bands permanently mounted in said rotor, said bands being imperforate save for a plurality of elongated transverse apertures formed therein, interchangeable means removably associated with said bands for obtaining any desired droplet dispersion within said rotor, retaining means on said bands for operationally retaining said first mentioned means, and access means in one of said end walls for affording access to said bands.

17. A centrifugal countercurrent exchange device comprising a rotor having an imperforate outer cylindrical wall and a pair of end walls, a plurality of spaced separator bands permanently mounted in said rotor with the marginal edges thereof being received in concentric grooves formed in said end walls, said bands being formed with a plurality of rows of elongated apertures spaced one from the other and extending substantially but less than the distance between said end walls, said bands being otherwise imperforate, a pair of opposed elongated channel members secured to the inner surface of said bands adjacent each of said rows of elongated apertures, a plurality of elongated strips having varying aperture characteristics formed therethrough, each of said strips being slidably engageable in one of said pairs of opposed channel members to cover the adjacent row of elongated apertures and thereby afford complete adjustability over the aperture characteristics in said rotor, a plurality of access ports formed in one of said end Walls, said access ports being arranged so that access is provided to all of said bands and elongated apertures, a disc removably positioned in each of said ports and comprising a cut-out section of said one end wall, and a sealing plug removably positioned in each of said ports and bearing against said disc when operationally positioned.

18. In a centrifugal countercurrent exchange device, including a rotor having a pair of end walls and a plurality of separator bands positioned in said rotor, means for supplying heavier liquid to and means for removing lighter liquid from the interior of said rotor in the proximity of the axis thereof, and means for forcing lighter liquids into and means for discharging heavier liquids from the interior of said rotor in the proximity of the periphery thereof; the herein improvement comprising: a plurality of access ports formed in one of said end walls, and removable means associated with said access ports of said end wall, whereby said removable means can be removed from said access ports for gaining access to the interior of said rotor.

19. A centrifugal countercurrent exchange device, as defined in claim 18, in which said removable means comprises a disc that is removably positioned in each of said access ports, said disc comprising a cutout section of said end wall and having a plurality of grooves therein adapted to accommodate the edges of said bands.

20. The centrifugal countercurrent exchange device as defined in claim 18 in which said access ports are radian shaped, a radiant shaped disc removably positioned in each of said ports and comprising a cutout section of said one end Wall, said disc having a plurality of spaced grooves formed therein, said grooves adapted to engage the edges of said bands.

References Cited by the Examiner UNITED STATES PATENTS 762,625 6/1904 Eck 233-43 2,619,280 11/1952 Redlich 233-15 2,710,790 6/1955 Rupp et al. 23-2705 3,114,706 12/1963 Podbielniak 23315 M. CARY NELSON, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,21 ,980 November 16, 1965 Wladzia G. Podbielniak et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 19, for "effiicacious" read efficacious column 2, line 37, for "orfii ces" read orifices column 6, line 61, for "first" read fifth line 72, for "second" read sixth column 9, line 3, for "radiant" read radian i Signed and sealed this 26th day of November 1968.

iEAL) ttest:

Elward M. Fletcher, Jr. EDWARD J. BRENNER ttestin g Officer Commissioner of Patents 

1. IN A CENTRIFUGAL COUNTERCURRENT EXCHANGE DEVICE, INCLUDING A ROTOR HAVING A PAIR OF END WALLS AND A PLURALITY OF CONCENTRIC SEPARATOR BANDS POSITIONED IN SAID ROTOR, MEANS FOR SUPPLYING HEAVIER LIQUID TO AND MEANS FOR REMOVING LIGHTER LIQUID FROM THE INTERIOR OF SAID ROTOR IN THE PROXIMITY OF THE AXIS THEREOF, AND MEANS FOR FORCING LIGHTER LIQUID INTO AND MEANS FOR DISCHARGING HEAVIER LIQUID FROM THE INTERIOR OF SAID ROTOR IN THE PROXIMITY OF THE PERIPHERY THEREOF; THE HEREIN IMPROVEMENT COMPRISING MEANS REMOVABLY ASSOCIATED WITH SAID SEPARATOR BANDS FOR ADJUSTING THE APERTURE CHARACTERISTICS THEREOF, AND REMOVABLE MEANS IN ONE OF SAID END WALLS AFFORDING ACCESS TO SAID BANDS FOR MAKING SAID ADJUSTMENTS. 